There is known a technique called augmented reality (AR) for presenting information additionally to a real object, which is an object present in the real world, using a computer. In the augmented reality, the information displayed additionally to the real object is also called “virtual object”. Functions of the augmented reality are mounted on a head mounted display (hereinafter referred to as “HMD” or “head-mounted display device”).
The HMD picks up an image of an outside scene with a camera, recognizes the image obtained by the image pickup, and generates or acquires a virtual object. A transmissive HMD, which does not block the visual field of a user in a mounted state of the HMD, causes the user to visually recognize only a virtual image including a virtual object. The user can experience the augmented reality by viewing both of a real object in the real world and the virtual object represented by the virtual image. PTL 1 describes a technique for aligning a display region of the virtual image and an image pickup region of the camera in the transmissive HMD to reduce a sense of discomfort that the user feels when the augmented reality is realized.